Birchy, I use thease timeing pullys on my mill conversion http://uk.rs-online.com/web/search/s...duct&R=182-694 RS generaly arent the cheepest but there service is second to none and delivery is free (normaly next day). i used a 1:4 ratio but im only useing 205 oz-in steppers so your 425 oz-in steppers should work well on the 1:2 ratio you were thinking of useing. i also used the original leadscrews (5mm pitch i think mine are). the max speed i get with my 1:4 ratio is 1800mm/min so its pritty slow but does get the job done. this was only a temporary conversion to help me cut parts for the router/plasma table im makeing. i will buy a new mill with a vertical dove tail colum to do a proper permanant conversion on after i finished my currant project. btw my mill is a Champion mill from chester uk.


Hope this helps

regards
Simon